Muddy Waters was one of those rare musicians whose impact and influence transcends their own body of work. In his case, as the acknowledged giant of electric blues, Waters became a cultural icon emblematic of the mid-century emancipatory migration north from the cotton fields of Mississippi to the stockyards and factories of Chicago, a move he made in 1943. This four-disc set covers the first decade and a half of his career, from his earliest field recordings made for Alan Lomax in 1941 - the archivist had been searching for Robert Johnson, and eventually turned his attention to Waters when it transpired that Johnson was long dead - to the awesome power of the Chess recordings that thrust him into the R&B mainstream, such as "Mannish Boy" and "I'm Your Hoochie Coochie Man". The change in impact as Waters moved from acoustic guitar to electric can best be tracked in the transformation of the 1941 country blues "I Be's Troubled" into the sleek and upholstered "I Can't Be Satisfied" that provided Waters with his first hit in 1948: the same lyric, the same bottleneck licks, but it's like comparing a dusty pick-up truck to a shiny black Cadillac.